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© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 1
11091 PS6
Advanced SMPS Applications using the dsPIC®
DSC SMPS Family
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 2
Class Objective
When you finish this class you will: Understand design considerations for a
High Power Converter Know how to implement digital control
loops using the dsPIC® DSC Understand the benefits of Digital Power
Conversion View a demonstration of the AC/DC
Reference Design
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 3
Agenda
Overview of AC/DC Reference Design AC/DC Reference Design Architecture Power Factor Correction
PFC Control Software Zero Voltage Transition
ZVT Control Software Multi-phase Buck Converters
Multi-phase Buck Control Software Enhanced Features
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 4
Agenda
Overview of AC/DC Reference Design AC/DC Reference Design Architecture Power Factor Correction
PFC Control Software Zero Voltage Transition
ZVT Control Software Multi-phase Buck Converters
Multi-phase Buck Control Software Enhanced Features
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 5
Overview of the AC/DC Reference
Design
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 6
Overview of AC/DC Reference Design
Total Output Power Rating of 350 W Multiple DC Outputs:
3.3V, 69A (max) 5V, 23A (max) 12V, 28A (max)
Universal Operating Voltage 85V – 265V AC, 45-65 Hz
Digital PFC Implementation PF > 0.98
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 7
Overview of AC/DC Reference Design
Automatic Fault Handling Flexible Start-up Capability Remote Power Management
Capability Full Digital Control
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 8
AC/DC Reference Design Block Diagram
85-265Vac 45-65Hz
EMI Filter and Bridge
Rectifier
PFC Boost
Converter
ZVTFull-BridgeConverter
Synchronous Rectifier
Opto- Coupler
3.3Vdc
69A
5Vdc
23A
Isolation Barrier
400Vdc 12Vdc
Rectified Sinusoidal
Voltage
Multi-Phase Buck Converter
Single-Phase Buck Converter
Phase Shift ZVT Converter
dsPIC30F2023
dsPIC30F2023
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 9
dsPIC® DSC SMPS Features 30 MIPS MCU + DSP core Intelligent Power Peripherals
High Speed A/D: 10-bit, 2 MSPS High Resolution PWM – 1.05ns High Speed Analog Comparators
Internal Fast RC oscillator + PLL Small footprint package - 6 x 6 mm Flash-based controller CodeGuard™ Security Enabled Extended Temp (125°C) Operation Additional Information in 11089_PS4
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 10
Agenda
Overview of AC/DC Reference Design AC/DC Reference Design Architecture Power Factor Correction
PFC Control Software Zero Voltage Transition
ZVT Control Software Multi-phase Buck Converters
Multi-phase Buck Control Software Enhanced Features
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 11
AC/DC Reference Design Architecture
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 12
Considerations for Choice of Architecture
Number of Stages Choice of PFC Topology Switching Methodology Output Isolation requirements Requirements of Output Stage
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 13
Considerations for Choice of Architecture
Number of Stages Choice of PFC Topology Switching Methodology Output Isolation requirements Requirements of Output Stage
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 14
Synchronous Rectifier
Multi-Stage Architecture
Multi-stage design simplifies design of each stage
85-265Vac 45-65Hz
dsPIC30F2023
dsPIC30F2023
EMI Filter and Bridge
Rectifier
PFC Boost
Converter
ZVTFull-BridgeConverter
Opto- Coupler
3.3Vdc
69A
5Vdc
23A
Isolation Barrier
Rectified Sinusoidal
Voltage
Multi-Phase Buck Converter
Single-Phase Buck Converter
AC/DCReference
Design
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 15
Multi-Stage Architecture
85-265Vac 45-65Hz
dsPIC30F2023
dsPIC30F2023
EMI Filter and Bridge
Rectifier
PFC Boost
Converter
ZVTFull-BridgeConverter
Synchronous Rectifier
Opto- Coupler
3.3Vdc
69A
5Vdc
23A
Isolation Barrier
Rectified Sinusoidal
Voltage
Multi-Phase Buck Converter
Single-Phase Buck Converter
Multiple Outputs and multiple loads can be controlled Independently
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 16
Multi-Stage Architecture
Modular Architecture enables swapping of stages with drop-in topologies
85-265Vac 45-65Hz
dsPIC30F2023
dsPIC30F2023
EMI Filter and Bridge
Rectifier
PFC Boost
Converter
ZVTFull-BridgeConverter
Synchronous Rectifier
Opto- Coupler
3.3Vdc
69A
5Vdc
23A
Isolation Barrier
Rectified Sinusoidal
Voltage
Single-Phase Buck Converter
Half-BridgeConverterPush-PullConverter
Full-Wave Rectifier
Single-Phase Boost Converter
Single-Phase Buck Converter
Single-Phase Buck Converter
Single-Phase Buck Converter
Multi-Phase Buck Converter
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 17
Considerations for Choice of Architecture
Number of Stages Choice of PFC Topology Switching Methodology Output Isolation requirements Requirements of Output Stage
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 18
Buck-Boost Converter
Choice of PFC TopologyBuck Converter
v1
S
D
L
C
-
+
+
-
i
v2
SD
L C
-
+
-
+
i
v1 v2
v1
v1
i1
i1
V2 < V1
V2 < V1
V2 > V1
0
0
-ωt
ωt
ωt
ωt
Buck and Buck-Boost Topologies operate with discontinuous Current
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 19
Why PFC Boost Converter?
S
DL
C
-
+
+
-
i
v1v2
v1
i1
V2 > V1
0 ωt
ωt
Boost Converter
Boost Converter operates with continuous input current at high loads
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 20
Considerations for Choice of Architecture
Number of Stages Choice of PFC Topology Switching Methodology Output Isolation requirements Requirements of Output Stage
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 21
Choice of Switching Methodology
Hard Switching Soft Switching
Fixed Frequency Operation Variable/Fixed Frequency Operation
Fewer Components Required More Components Required
Simpler Control Complex Control
High Switching Losses Low Switching Losses
Used in Designs with Low Power and Low Performance
Requirements
Used in Designs with High Power and High Performance
Requirements
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 22
Considerations for Choice of Architecture
Number of Stages Choice of PFC Topology Switching Methodology Output Isolation requirements Requirements of Output Stage
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 23
dsPIC30F2023
dsPIC30F2023
Live Bias Supply
Isolated Bias Supply
Output Isolation and Safety Requirements
Output Isolation is provided by: Transformers Optocouplers
Isolation Barrier
Low Voltage OutputHigh
VoltageInput
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 24
Considerations for Choice of Architecture
Number of Stages Choice of PFC Topology Switching Methodology Output Isolation requirements Requirements of Output Stage
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 25
Output Stage Requirements
LOAD
LOAD
Buck Converter
Synchronous Buck Converter
Multi-Phase Synchronous Buck Converter
Output Design Specifications determine Choice of Converter Topology
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 26
Summary
Overview of AC/DC Reference Design Design Specifications Features of dsPIC® DSC SMPS Family
AC/DC Reference Design Architecture Block Diagram Rationale Behind Chosen Architecture
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 27
Agenda
Overview of AC/DC Reference Design AC/DC Reference Design Architecture Power Factor Correction
PFC Control Software Zero Voltage Transition
ZVT Control Software Multi-phase Buck Converters
Multi-phase Buck Control Software Enhanced Features
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 28
Power Factor Correction
Additional Information Available in 11092_PFC
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 29
Why is PFC needed?
Reduce Peak Current Ratings Reduce Component Overheating Efficiently utilize available Power Comply with Regulations Avoid Penalties from Utility
Company
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 30
What is Power Factor ?
Applied Voltage
Resulting Current
Φ Φ
Un-utilized power Applied Voltage
Resulting Current
Useful power
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 31
Power Factor Correction
AC
Load
With no Power Factor Correction, the input current is highly distorted
Induces Noise in the Power Grid
Higher current rating device is required
Current is not sinusoidal
Input Voltage
Output Voltage
Input Current
Diode ON Diode ON Diode ON Diode ON
Dio
de
OF
F
Dio
de
OF
F
Dio
de
OF
F
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 32
Power Factor Correction
P.F. = Real (Active) component of Power/Total Power Need to sense Vin, Inductor Current and Vhb
Maintains a Noise-free power grid Reduce rms and peak current required by the system
Boost Circuit
Forced Sinusoidal
input current
Input Voltage
Input Current
AC
Load
VVinin
VVhbhb
IIinin
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 33
Common PFC Methods
Input Current
Input Current
Discontinuous Current Mode
Critical Conduction Current Mode
Continuous Current Mode
Input Current
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 34
PFC Boost Converter
++
--~~ ~~
Vac
C2
R1
R2
R4
R5
R3 R6
Rsense
-HV_BUS
+HV_BUS
C1 C4
L1
Q1
D1
PWM1H
|VAC| Sense
VHV Sense
IPFC sense
C3
Primary (Live) Side
LIVE_GNDPFC
MOSFET
Boost Diode
PFC Inductor
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 35
∑+
-
PFC Control Scheme
Voltage Reference
Vout
PFC Choke
Voltage Feedback
PWM
Current Feedback
PFC Current sense
VOUT Sense
Voltage Error Compensator
ADC
1001011011
1011001010
Current Error Compensator∑
+-
X
Rectified AC Mains Voltage
Calculated Current
Reference
2
1
V|VAC|MEAN
S&H
S&H
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 36
Resources Required for Digital PFC
VAC
IPFCVHV_BUS
dsPIC30F2023
ADC Channel
ADC Channel
ADC Channel
PWM Output
|VAC|
k1
k2
k3
FETDriver
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 37
PFC Resource AllocationSignal Name Type of
SignaldsPIC® DSC
Resource UsedVOUT
Analog Input AN5
IPFCAnalog Input AN4
|VAC| Analog Input AN6
MOSFET Gate Drive
Drive Output PWM4L
Current Loop Trigger
dsPIC® DSC Internal Signal
PWM4 Trigger to Sample PFC Current
Voltage Loop Trigger
dsPIC® DSC Internal Signal
Timer2
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 38
Agenda
Overview of AC/DC Reference Design AC/DC Reference Design Architecture Power Factor Correction
PFC Control Software Zero Voltage Transition
ZVT Control Software Multi-phase Buck Converters
Multi-phase Buck Control Software Enhanced Features
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 39
PFC Control Software
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 40
PFC Software Overview ADC Conversions are initiated by the
PWM Trigger Feature The Current Control Loop is
Executed in the ADC Interrupt Routine
The Voltage Loop is Executed in a Timer Interrupt
Faults are handled by the PWM Module using the on-chip Analog Comparators
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 41
Structure of the PFC Software
Initialize PWM Initialize ADC Setup Timer Configure
Interrupts Initialize Control
Loop Variables
Initialization
Start
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 42
Structure of the PFC Software
Initialize PWM Configure PWM Mode,
Output Polarity, Period, initial Duty Cycle
Setup PWM Faults and Fault Thresholds
Setup PWM Triggers
Initialization
Start
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 43
Structure of the PFC Software
Initialize ADC Setup ADC Speed Configure desired
ADC channels as analog inputs
Choose ADC Trigger Sources
Configure ADC Data Format
Choose Simultaneous or Sequential Sampling
Initialization
Start
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 44
Structure of the PFC Software
Configure Timer Use Timer to trigger
Voltage Control Loop Setup Interrupts
PWM Interrupt for Fault Handling
ADC Interrupt to trigger Current Control Loop
Timer Interrupt to trigger Voltage Control Loop
Initialization
Start
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 45
Structure of the PFC Software
Initialize Control Loop Variables Initialize PID Gain
Terms in X-memory Initialize Measured
signals in Y-memory Initialize pointers to
Control Loop Inputs and Outputs
Initialization
Start
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 46
Structure of the PFC Software
Enable Peripherals Enable Timer Enable ADC Enable PWM
Initialization
Start
Enable Peripherals
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 47
Structure of the PFC Software Check for Faults
The PWM Module is setup to detect Faults and Shutdown all Outputs
The PWM Fault Interrupt sets the Fault Flag
The Main Routine Checks the Fault Flag
Initialization
Start
Enable Peripherals
Fault Presen
t?
Fault Loop
Fault Loop The Fault Indicator LED
is enabled Any other Fault Handling
Routines can be placed in this loop
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 48
Structure of the PFC Software
Idle Loop(Low Priority) Input AC Voltage
Measurement Power Management
Routines Check Temperature Other Auxiliary
Features
Initialization
Start
Idle Loop(Normal
Operation)
Enable Peripherals
Fault Presen
t?
Fault Loop
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 49
ADC Interrupt(High Priority) PFC Current Loop
PFC Current Measurement
Current PID Calculations
Update PWM Duty Cycle
Structure of the PFC Software
Initialization
Start
Idle Loop(Normal
Operation)
Enable Peripherals
Fault Presen
t?
Fault Loop
ADC Interrupt
Timer Interrupt(Medium Priority) PFC Voltage Loop
VOUT Measurement Voltage PID
Calculations Update PFC Current
ReferenceTimer Interrupt
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 50
Demonstration #1
Digital Power Factor Correction
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 51
Agenda
Overview of AC/DC Reference Design AC/DC Reference Design Architecture Power Factor Correction
PFC Control Software Zero Voltage Transition
ZVT Control Software Multi-phase Buck Converters
Multi-phase Buck Control Software Enhanced Features
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 52
Zero Voltage andZero Current Switching
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 53
Zero Voltage Switching At transition period from one state to
another state of the switch, the voltage is zero, hence no losses
t
t
Id
Vds
Vds(t)
Id(t)
PWM
ZVS
D
S
G
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 54
Zero Voltage Switching : Eliminates V*I losses in switching device
during transitions Reduces Noise in the system hence
better EMI performance Eliminates MOSFET output capacitor
(Coss) loss during switch Turn-ON Preferred in high voltage high power
system
Switching Methodology
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 55
At transition period from one state to another state of the switch, current is zero, hence no losses
t
t
Vds
Vds(t)
Ir(t)
ZCS
PWM
Zero Current Switching
D
S
G
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 56
Zero Current Switching: Eliminates V*I losses in switching device
during transitions Reduces Noise in the system hence
better EMI performance Can be implemented at switch Turn ON
as well as Turn OFF RMS Current through switch increases
and therefore higher conduction losses
Switching Methodology
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 57
Soft Switching Topologies Resonant Mode
SRC – Series Resonant PRC – Parallel
Resonant LLC Resonant
Series Resonant Half Bridge
Converter PWM1H
+Vin
LR VoutT1
PWM1L CR
Zero Transition ZVT – Zero Voltage
Transition
Full Bridge ZVT Converter
Resonant Circuit
PWM1H
PWM1L PWM2L
PWM2H
+Vin
T1
L1
Vout
Phase Shift Element
Lm
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 58
Full-Bridge ZVT Converter
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 59
Full-Bridge Converter
PWM1H
PWM1L
PWM1L
PWM1H
+Vin
T1 L1 Vout
Full bridge converter Buck derived isolated converter Push Pull mode of PWM gate pulses Each half-bridge produces square wave
voltage Duty cycle ratio controls the power flow Turn ON as well as Turn OFF losses in the
MOSFET Popular for high power application
PWM1H
PWM1L
Vpri
Ipri
VpriIpri
tt
tt
tt
tt
Ts
ton
Ts/2
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 61
Full-Bridge Phase Shift ZVT Converter
Full-bridge Phase Shift ZVT converter Complementary, fixed duty cycle PWM gate pulses Phase shift in gate pulse of two legs control the power flow Zero Voltage Switching, hence Turn ON losses in the
MOSFET eliminates Parasitic of MOSFET and Transformer used to achieved
ZVT A popular converter for very high power application
PWM1H
PWM1L
PWM2H
PWM2L
+Vin
T1 L1 Vout
VVpripri
IIpripri
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 62
Full-Bridge Phase Shift ZVT Converter
+Vin
T1
L1
Vout
Right leg transition Terminates the power delivery interval
Reflected load current is driving ZVS
Transition is linear
End of this period transformer primary is short circuited
IIpripri
A
B D
C
A
B
D
C
VT
VT
E
F
VT
IIpripri
Left leg transition Begins after freewheeling state to initiate the
power delivery
Energy stored in the inductor drives the ZVS
Transition is resonant and non linear
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 63
rCLdt 12
The right leg transition period is given by: Time required to charge and discharge the output capacitor of
MOSFET C and MOSFET D
The left leg transition period is given by: Resonant time between L1 and output capacitor of MOSFET (A+B)
pr I
dvCdt
Where, dt = transition time
Ip = primary current when the MOSFET D turns OFF
L1 = Leakage inductance of transformer
Cr = equivalent capacitor of MOSFET two MOSFET and transformer parasitic capacitor (Cxfmr)
Full-Bridge Phase Shift ZVT Converter
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 64
∑+
-
ZVT Control Scheme
Voltage Reference
Vout
ZVT Xformer
Voltage Feedback
PWM Phase
Current Feedback
ZVT Current sense
VOUT Sense
Voltage Error Compensator
ADC
1001011011
1011001010
Current Error Compensator∑
+-
Calculated Current
Reference
S&H
S&H
Rectifier
Optocoupler
S&H
1001001001
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 65
Resources Required for Digital ZVT Converter
dsPIC30F2023
k1
k2
dsPIC30F2023
ADC Channel
ADC Channel
UART TX
PWM
UART RX
PWM
PW
M
IZVT
VHV_BUS VOUT
Isolation Barrier
ADC Channel
PW
M
PW
M
PW
M
FETDriver FET
Driver FETDriver
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 66
ZVT Resource AllocationSignal Name Type of
SignaldsPIC® DSC
Resource UsedIZVT1
Analog Input AN0
IZVT2Analog Input AN2
VOUTUART Input U1RX
ZVT Gate Drive Drive Outputs PWM1H, PWM1L PWM2H, PWM2L
Sync. Rectifier Gate Drive
Drive Outputs PWM3H, PWM3L
Current Loop Trigger
dsPIC® DSC Internal Signal
PWM1, PWM2 Triggers to Sample ZVT Current
Voltage Loop Trigger
dsPIC® DSC Internal Signal
UART1
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 67
Agenda
Overview of AC/DC Reference Design AC/DC Reference Design Architecture Power Factor Correction
PFC Control Software Zero Voltage Transition
ZVT Control Software Multi-phase Buck Converters
Multi-phase Buck Control Software Enhanced Features
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 68
ZVT Control Software
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 69
ZVT Software Overview ADC Conversions are initiated by the
PWM Trigger Feature The Current Control Loop is Executed in
the ADC Interrupt Routine Additional Check for Transformer Primary
Current Balance to prevent Flux Walking The Voltage Loop is Executed from a
UART Receive Interrupt Faults are handled by the PWM Module
using the on-chip Analog Comparators
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 70
Structure of the ZVT Software
Initialize PWM Initialize ADC Setup Timers Setup UART Configure
Interrupts Initialize Control
Loop Variables
Initialization
Start
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 71
Structure of the ZVT Software
Initialize PWM Configure PWM
Mode, Output Polarity, Period, Duty Cycle and Phase Shift
Setup PWM Faults and Fault Thresholds
Setup PWM Triggers
Initialization
Start
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 72
Structure of the ZVT Software
Initialize ADC Setup ADC Speed Configure desired
ADC channels as analog inputs
Choose ADC Trigger Sources
Configure ADC Data Format
Choose Simultaneous or Sequential Sampling
Initialization
Start
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 73
Structure of the ZVT Software Configure Timers
Use Timer to trigger Voltage Control Loop
Configure UART Use UART to receive
VOUT feedback signal Setup Interrupts
PWM Interrupt for Fault Handling
Timer Interrupt to trigger Voltage Control Loop
ADC Interrupt to trigger Current Control Loop
UART Receive Interrupt to Execute the Voltage Loop
Initialization
Start
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 74
Structure of the ZVT Software
Initialize Control Loop Variables Initialize PID Gain
Terms in X-memory Initialize Measured
signals in Y-memory Initialize pointers to
Control Loop Inputs and Outputs
Initialization
Start
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 75
Structure of the ZVT Software
Enable Peripherals Enable Timers Enable UART Enable ADC Enable PWM
Initialization
Start
Enable Peripherals
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 76
Structure of the ZVT Software Check for Faults
The PWM Module is setup to detect Faults and Shutdown all Outputs
The PWM Fault Interrupt sets the Fault Flag
The Main Routine Checks the Fault Flag
Initialization
Start
Enable Peripherals
Fault Presen
t?
Fault Loop
Fault Loop The Fault Indicator LED
is enabled Any other Fault Handling
Routines can be placed in this loop
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 77
Structure of the ZVT Software
Idle Loop(Low Priority) Check Input
Voltage Check
Temperature Power
Management Routines
Other Auxiliary Features
Initialization
Start
Idle Loop(Normal
Operation)
Enable Peripherals
Fault Presen
t?
Fault Loop
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 78
Structure of the ZVT Software ADC Interrupt
(High Priority) ZVT Current Loop
ZVT Current Measurements
Check for Current Imbalance
Current PID Calculations
Update Phase Shift
Initialization
Start
Idle Loop(Normal
Operation)
Enable Peripherals
Fault Presen
t?
Fault Loop
ADC Interrupt
UART Interrupt(Medium Priority) ZVT Voltage Loop
VOUT Measurement ZVT Voltage PID
Calculations Update ZVT Current
ReferenceUART Interrupt
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 79
Additional Guidelines for Primary side
dsPIC® DSC Software
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 80
Full-Bridge Phase Shift ZVT Converter
ZVT Current #1 Trigger Instant Trigger at start of
PWM1H Pulse
+Vin
T1
L1
Vout
IIpripri
PWM1H
PWM1L PWM2L
PWM2H
VT
E
F
ZVT Current #2 Trigger Instant Trigger on PWM2H at
(Duty Cycle + Phase Shift)
PWM1H
PWM1L
Ipri
PhaseShift
PWM2H
PWM2LDuty Cycle
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 81
Sequence of Current Loop Triggers
PWM1H
PWM1L
PWM2H
PWM2L
PWM4L
ZVT Current 1Trigger:
Once every 8ZVT cycles
ZVT Current 2Trigger:
Once every 8ZVT cycles
PFC CurrentTrigger:
Once every 4PFC cycles
Execute ZVT
Current Loop #1
Sample and
ConvertAN0, AN1
Sample and
ConvertAN2, AN3
Execute ZVT
Current Loop #2
Idle Loop
Sample and
ConvertAN4, AN5
Execute PFC
Current Loop
Idle Loop
Idle Loop
Execute ZVT
Current Loop #1
Sample and
ConvertAN0, AN1
ZVT Current 1Trigger:
Once every 8ZVT cycles
Phase Shift
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 82
Time Management
Idle time between execution of consecutive ZVT Current Loops should be large enough to prevent multiple simultaneous ADC Triggers
Worst Case Condition is Maximum Phase Shift
PWM1H
PWM1L
PWM2H
PWM2L
PWM3L
ZVT Current 1Trigger:
Once every 8ZVT cycles
Execute ZVT
Current Loop #1
Sample and
ConvertAN0, AN1
ZVT Current 2Trigger:
Once every 8ZVT cycles
Sample and
ConvertAN2, AN3
Execute ZVT
Current Loop #2
Phase Shift
Idle Loop
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 83
Time Management
The Idle time after execution of the second ZVT Current Loop should be enough to prevent multiple simultaneous ADC Triggers
Worst Case condition is zero Phase Shift
PWM1H
PWM1L
PWM2H
PWM2L
PWM3L
PWM1H
PWM1L
PWM2H
PWM2L
PWM4L
ZVT Current 1Trigger:
Once every 8ZVT cycles
ZVT Current 2Trigger:
Once every 8ZVT cycles
PFC CurrentTrigger:
Once every 4PFC cycles
Execute ZVT
Current Loop #1
Sample and
ConvertAN0, AN1
Sample and
ConvertAN2, AN3
Execute ZVT
Current Loop #2
Idle Loop
Sample and
ConvertAN4, AN5
Execute PFC
Current Loop
Idle Loop
Phase Shift
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 84
Time Management
The Idle time after PFC Current Loop Execution utilized for executing the Voltage Loops and auxiliary functions
PWM1H
PWM1L
PWM2H
PWM2L
PWM3L
PWM1H
PWM1L
PWM2H
PWM2L
PWM4L
ZVT Current 1Trigger:
Once every 8ZVT cycles
ZVT Current 2Trigger:
Once every 8ZVT cycles
PFC CurrentTrigger:
Once every 4PFC cycles
Execute ZVT
Current Loop #1
Sample and
ConvertAN0, AN1
Sample and
ConvertAN2, AN3
Execute ZVT
Current Loop #2
Idle Loop
Sample and
ConvertAN4, AN5
Execute PFC
Current Loop
Idle Loop
Idle Loop
Phase Shift
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 85
Control Loop ExecutionPID Control Loop
Kp
Ki Σe(n)
Kdde(n) /dn
PWMe(n)x(n) y(n)u(n)
+-+
up(n)
ui(n)
ud(n)
u(n) = up(n) + ui(n) + ud(n)where,up(n) = Kp*e(n)ui(n) = Ki*[e(n) + e(n-1)]ud(n) = Kd*[e(n) - e(n-1)]
+
Reference Input
Error Signal
PID Command
(correction)
Measured Output
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 86
Auxillary Tasks
AC Input Voltage Measurement Check if Soft Start is required Temperature Measurement Communication Routines
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 87
Demonstration #2
ZVT Operation
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 88
Summary Power Factor Correction
Overview of PFC Control Scheme for Digital PFC Structure of Control Software
Zero Voltage Transition ZVS and ZCS and Full-Bridge Converter ZVT Phase Shift Converter Control Scheme for ZVT Converter Structure of Control Software
Additional Guidelines for Primary Side dsPIC® DSC Control Software Time Management
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 89
Agenda
Overview of AC/DC Reference Design AC/DC Reference Design Architecture Power Factor Correction
PFC Control Software Zero Voltage Transition
ZVT Control Software Multi-phase Buck Converters
Multi-phase Buck Control Software Enhanced Features
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 90
Multi-Phase Buck Converter
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 91
Basic Theory of a Buck Converter
Step down converter
ON
+Vin
L1 Vout
CoutCin
Q1
IQ IL
PWM
PWMTon Toff
Period
Switch ONSwitch ONCharging inductor
D1
ILoad
Iripple
IL
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 92
Basic Theory of a Buck Converter
Step down converter
+Vin
L1 Vout
CoutCin
Q1
OFF
IL
IDPWM
PWMTon Toff
Period
Switch OFFSwitch OFFSwitch OFFSwitch OFFDischarging inductor
D1
ILoad
Iripple
IL
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 93
Vout = Vin D
Where:D = PWM dutycycle = Ton / (Ton +Toff)
Note: range of duty cycle = 0 to 1
PWM Pulse Width vs. Buck Output Voltage
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 94
Synchronous Buck Converter
PWMH
PWML
Period
+Vin
L1
Vout
CoutCin
Q1ILOAD + Iripple
ILOAD
PWMH Iripple
Q2
PWML
Iripple
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 95
Multi-Phase Buck Converter
12V Input
3.3VOutput
GND
Q1Q2
Q3Q4
Q5Q6
120° 120° 120°
Q1
Q3
Q5
Drive Signals are Phase
Shifted by 120°
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 96
Why the Multi-phase Buck Converter?
Each Phase is rated for less Power Semiconductor Devices have lower
current rating Smaller MOSFETs usually mean better
switching speed Higher Output Ripple Frequency
decreases size of output filter Ripple magnitude is reduced
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 97
∑+
-
5V Buck Converter Control Scheme
Voltage Reference VOUT
Buck Inductor
Voltage Feedback
PWM
Buck Current sense
VOUT Sense
Voltage Error Compensator
ADC
1001011011
S&H
Analog Comparator
+-
Vref
Calculated Current
Reference
Current Limit Shutdown
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 98
∑+
-
3.3V Buck Converter Control Scheme
Voltage Reference
VOUT
Phase 3 Inductor
Voltage Feedback
PWM
Buck Current sense 1
VOUT Sense
Voltage Error Compensator
ADC
1001011011
S&H
Analog Comparator
+-
Vref
Phase 2 Inductor
Phase 1 Inductor
Analog Comparator
+-
Vref
Analog Comparator
+-
Vref
Buck Current sense 2
Buck Current sense 3
Calculated Current
Reference
Current Limit Shutdown
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 99
Resources Required for Digital Buck Converters
k1
dsPIC30F2023
Analog Comp.
UART TX
k5
k2
k4
k3
k6k7
PW
MP
WM ADC
Channel
Analog Comp.Analog Comp.ADC
Channel
Analog Comp.
ADC Channel
PW
MP
WM
PWMPWM
PW
MP
WM
3.3VOutput
5VOutput
I5V
I3.3V_1
I3.3V_2
I3.3V_3
12VInput
FET Driver
FET Driver
FET Driver
FET Driver
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 100
Buck Converters Resource Allocation
Signal Name Type of Signal
dsPIC® DSC Resource Used
I5VAnalog Input CMP1A
5V Output Analog Input AN1
I3.3V_1Analog Input CMP2A
I3.3V_2Analog Input CMP3A
I3.3V_3Analog Input CMP4A
3.3V Output Analog Input AN3
5V Buck Gate Drive
Drive Outputs PWM4H, PWM4L
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 101
Buck Converters Resource Allocation
Signal Name Type of Signal
dsPIC® DSC Resource Used
3.3V Buck Gate Drive
Drive Outputs PWM1H, PWM1L
PWM2H, PWM2L
PWM3H, PWM3L
5V Current Loop Trigger
dsPIC® DSC Internal Signal
PWM4 Trigger to Sample 5V Buck Voltage
3.3V Current Loop Trigger
dsPIC® DSC Internal Signal
PWM1 Trigger to Sample 3.3V Buck Voltage
12V Bus Sense Analog Input AN5
12V Digital Feedback
UART Transmission
U1TX
Temperature Sense
Analog Input AN8
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 102
Agenda
Overview of AC/DC Reference Design AC/DC Reference Design Architecture Power Factor Correction
PFC Control Software Zero Voltage Transition
ZVT Control Software Multi-phase Buck Converters
Multi-phase Buck Control Software Enhanced Features
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 103
Multi-Phase Buck Converter Control Software
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 104
Multi-Phase Buck Converter Software Overview
ADC Conversions are initiated by the PWM Trigger Feature
Peak Current Control is implemented using the Analog Comparators Additional Check Desired for Current Imbalance
between the three phases The Voltage and Current Loops are
executed at the same speed The UART Transmission for 12V digital
feedback is executed from a Timer Interrupt
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 105
Structure of the Multi-Phase Buck Software
Initialize PWM Initialize ADC Initialize Analog
Comparators Setup Timers Configure UART Configure
Interrupts Initialize Control
Loop Variables
Initialization
Start
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 106
Structure of the Multi-Phase Buck Software
Initialize PWM Configure PWM Mode,
Output Polarity, Period, Duty Cycle and Phase Shift
Setup PWM Current Limit Sources
Setup PWM Triggers
Initialization
Start
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 107
Structure of the Multi-Phase Buck Software
Initialize ADC Setup ADC Speed Configure desired
ADC channels as analog inputs
Choose ADC Trigger Sources
Configure ADC Data Format
Choose Simultaneous or Sequential Sampling
Initialization
Start
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 108
Structure of the Multi-Phase Buck Software
Initialize Analog Comparators Configure Correct
Analog Comparator Inputs
Choose Voltage Reference Source
Setup Initial DAC Reference
Choose Comparator Output Polarity
Initialization
Start
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 109
Structure of the Multi-Phase Buck Software
Configure UART Use UART to transmit
12V Bus Data to Primary Side dsPIC® DSC
Setup Interrupts PWM Interrupt for Fault
Handling Timer Interrupt to trigger
Voltage Control Loop ADC Interrupt to trigger
Current Control Loop
Initialization
Start
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 110
Structure of the Multi-Phase Buck Software
Initialize Control Loop Variables Initialize PID Gain
Terms in X-memory Initialize Measured
signals in Y-memory Initialize pointers to
Control Loop Inputs and Outputs
Initialization
Start
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 111
Structure of the Multi-Phase Buck Software
Enable Peripherals Enable Analog
Comparators Enable ADC Enable PWM Enable UART
Initialization
Start
Enable Peripherals
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 112
Structure of the Multi-Phase Buck Software
Check for Faults The PWM Module is
setup to detect Faults and Shutdown all Outputs
The PWM Fault Interrupt sets the Fault Flag
The Main Routine Checks the Fault Flag
Initialization
Start
Enable Peripherals
Fault Presen
t?
Fault Loop
Fault Loop The Fault Indicator LED
is enabled Any other Fault Handling
Routines can be placed in this loop
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 113
Structure of the Multi-Phase Buck Software
Idle Loop(Low Priority) Transmit 12V Bus
Data Power
Management Routines
Check Temperature
Other Auxiliary Features
Initialization
Start
Idle Loop(Normal
Operation)
Enable Peripherals
Fault Presen
t?
Fault Loop
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 114
Structure of the Multi-Phase Buck Software
ADC Interrupt(High Priority) Buck Current Loop
VOUT Measurement Calculate Current
Reference Update Analog
Comparator DAC References
Initialization
Start
Idle Loop(Normal
Operation)
Enable Peripherals
Fault Presen
t?
Fault Loop
ADC Interrupt
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 115
Structure of the Multi-Phase Buck Software
ADC Interrupt(High Priority) Buck Current Loop
VOUT Measurement Calculate Current
Reference Update Analog
Comparator DAC References
Initialization
Start
Idle Loop(Normal
Operation)
Enable Peripherals
Fault Presen
t?
Fault Loop
ADC Interrupt
Timer Interrupt(Medium Priority) Buck Voltage Loop
Transmit 12V Digital Feedback Signal
Timer Interrupt
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 116
Sequence of Current Loop Triggers
PWM1HPWM1LPWM2HPWM2L
PWM3HPWM3LPWM4HPWM4L
3.3V BuckVoltage Trigger
Execute 3.3V Buck
Control Loop
Sample and
ConvertAN3
Idle Loop
Execute 5V Buck Control
Loop
Sample and
ConvertAN1
Idle Loop
5V BuckVoltage Trigger
Execute 5V Buck Control
Loop
Sample and
ConvertAN1
Idle Loop
5V BuckVoltage Trigger
3.3V BuckVoltage Trigger
Execute 3.3V Buck
Control Loop
Sample and
ConvertAN3
Idle Loop
Execute 5V Buck Control
Loop
Idle Loop
5V BuckVoltage Trigger
3.3V BuckVoltage Trigger
Execute 3.3V Buck
Control Loop
Sample and
ConvertAN3
Sample and
ConvertAN1
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 117
Sequence of Current Loop Triggers
PWM1HPWM1LPWM2HPWM2L
PWM3HPWM3LPWM4HPWM4L
3.3V BuckVoltage Trigger
Execute 3.3V Buck
Control Loop
Sample and
ConvertAN3
Idle Loop
Execute 5V Buck Control
Loop
Sample and
ConvertAN1
Idle Loop
5V BuckVoltage Trigger
Execute 5V Buck Control
Loop
5V BuckVoltage Trigger
Current Loop Execution must finish before next ADC Trigger
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 118
Sequence of Current Loop Triggers
PWM1HPWM1LPWM2HPWM2L
PWM3HPWM3LPWM4HPWM4L
3.3V BuckVoltage Trigger
Execute 3.3V Buck
Control Loop
Sample and
ConvertAN3
Idle Loop
Execute 5V Buck Control
Loop
Sample and
ConvertAN1
Idle Loop
5V BuckVoltage Trigger
Execute 5V Buck Control
Loop
5V BuckVoltage Trigger
Perform Auxiliary Tasks during the Idle Times
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 119
Control Loop ExecutionPID Control Loop
Kp
Ki Σe(n)
Kdde(n) /dn
PWMe(n)x(n) y(n)u(n)
+-+
up(n)
ui(n)
ud(n)
u(n) = up(n) + ui(n) + ud(n)where,up(n) = Kp*e(n)ui(n) = Ki*[e(n) + e(n-1)]ud(n) = Kd*[e(n) - e(n-1)]
+
Reference Input
Error Signal
PID Command
(correction)
Measured Output
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 120
Auxillary Tasks
12V Bus Voltage Measurement Communication Routines Load Sharing Routines Temperature Measurement Power Management Routines
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 121
Demonstration #3
High Power Operation
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 122
Enhanced Features
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 123
∑+
-
PFC Sinusoidal Reference
Voltage Reference
Vout
PFC Choke
Voltage Feedback
PWM
Current Feedback
PFC Current sense
VOUT Sense
Voltage Error Compensator
ADC
1001011011
1011001010
Current Error Compensator∑
+-
X
Rectified AC Mains Voltage
S&H
S&H
Sinusoidal Reference can be generated using a lookup table in software
Sync signal for detecting Zero
Crossings
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 124
HV Bias Supply
TNY277
-HV_BUS
+HV_BUS
D
S
F/B
Live Digital Supply
LIVE_GND
LIVE_GND
Live Drive Supply
+13V
+7V
Digital Supply
GND
GND
Drive Supply
+17V
+7V
High Voltage Bus (400V)
Energy Efficient
Switching Converter
Bias Supplies
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 125
DSC to DSC Communication
Perform status checks
Report Fault Conditions to protect Hardware
Implement Data Logging and Remote Monitoring
dsPIC
30F2023 ds
PIC
30F
2023
U1TX
U1RX
U1RX
U1TX
Isolation Barrier
Primary (Live) Side
Secondary (Isolated)
Side
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 126
Power Supply Sequencing
Choose method that meets system requirements
3.3v
5.0vV
T
simultaneous
3.3v
5.0vV
T
sequential
3.3v
5.0vV
T
ratio metric
3.3v
5.0vV
T
offset
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 127
Output Protection Schemes
A number of protection schemes can be implemented Constant Current Limiting Constant Power Limiting Output Over-voltage Shutdown Input Under-voltage Shutdown
All shutdown schemes can be configured for immediate or delayed shutdown
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 128
Synchronous ZVT Converter
Remote Monitoring Capability
Power monitoring can be implemented using a Serial I2C™ interface provided on the Secondary (Isolated) side
PICkit™Serial
Analyzer
+VGNDSDASCK
85-265Vac 45-65Hz
dsPIC30F2023
dsPIC30F2023
EMI Filter and Bridge
Rectifier
PFC Boost
Converter
ZVTFull-BridgeConverter
Synchronous Rectifier
Opto- Coupler
3.3Vdc
69A
5Vdc
23A
Isolation Barrier
400Vdc 12Vdc
Rectified Sinusoidal
VoltageMulti-Phase
Buck Converter
Single-Phase Buck Converter
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 129
Load Sharing Issues Multiple power modules share load Component and wiring differences cause some
modules to work harder than others The heavily loaded modules get hotter and
reliability drops causing failures – Domino Effect
Buck Phase 1
LoadLoad Equalization
Routine
Buck Phase 2
Buck Phase 3
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 130
Benefits of Digital Control
Reduce Component Count Flexibility of Design Flexibility of Control Protect Intellectual Property Implement non-linear and adaptive
control Control Multiple Stages Error logging capability Flexible Fault handling
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 131
Summary
Overview of AC/DC Reference Design AC/DC Reference Design Architecture Power Factor Correction
PFC Control Software Zero Voltage Transition
ZVT Control Software Multi-phase Buck Converters
Multi-phase Buck Control Software Enhanced Features
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 132
AC/DC Reference Design Availability
Q4 2007 Contact Local Sales office for more
information Visit Microchip’s Intelligent Power
Supply Design Center for our full product offering www.microchip.com/smps
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 133
References C.K. Tse, “Circuit Theory of Power Factor Correction in switching
converters” A. Hofmann, A.Baumuller, T. Gerhardt, M. Marz, E. Schimanek, “A
robust digital PFC control method suitable for low-cost microcontroller”
L. Rossetto, G.Spiazzi, P. Tenti, “Control Techniques for Power Factor Correction Converters”
L.Rossetto, G.Spiazzi, “Design Considerations on Current-Mode and Voltage-Mode control methods for Half-Bridge Converters”
W.Gu, J.Abu-Qahouq, S.Luo, I.Batarseh, “A ZVT-PWM single stage PFC converter with an active snubber”
M. Brown, “Power Supply Cookbook” M. Kazimierczuk, D. Czarkowski, “Resonant Power Converters”
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 134
Development Tools Used in this Class
Hardware Tools AC/DC Reference Design (not released) MPLAB® REAL ICE™ Emulator
(DV244005) MPLAB ICD2 (DV164005)
Software Tools MPLAB IDE 7.61 (SW007002) MPLAB C30 v3.01 (SW006012)
© 2007 Microchip Technology Incorporated. All Rights Reserved. 11091 PS6 Slide 135
TrademarksThe Microchip name and logo, the Microchip logo, Accuron, dsPIC, KeeLoq, KeeLoq logo, microID, MPLAB, PIC, PICmicro, PICSTART, PRO MATE, rfPIC and SmartShunt are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries.AmpLab, FilterLab, Linear Active Thermistor, Migratable Memory, MXDEV, MXLAB, SEEVAL, SmartSensor and The Embedded Control Solutions Company are registered trademarks of Microchip Technology Incorporated in the U.S.A.Analog-for-the-Digital Age, Application Maestro, CodeGuard, dsPICDEM, dsPICDEM.net, dsPICworks, ECAN, ECONOMONITOR, FanSense, FlexROM, fuzzyLAB, In‑Circuit Serial Programming, ICSP, ICEPIC, Mindi, MiWi, MPASM, MPLAB Certified logo, MPLIB, MPLINK, PICkit, PICDEM, PICDEM.net, PICLAB, PICtail, PowerCal, PowerInfo, PowerMate, PowerTool, REAL ICE, rfLAB, Select Mode, Smart Serial, SmartTel, Total Endurance, UNI/O, WiperLock and ZENA are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries.SQTP is a service mark of Microchip Technology Incorporated in the U.S.A.All other trademarks mentioned herein are property of their respective companies.